Palm oil mill effluent treatment and CO<Subscript>2</Subscript> sequestration by using microalgae—sustainable strategies for environmental protection

In this era of globalization, various products and technologies are being developed by the industries. While resources and energy are utilized from processes, wastes are being excreted through water streams, air, and ground. Without realizing it, environmental pollutions increase as the country develops. Effective technology is desired to create green factories that are able to overcome these issues. Wastewater is classified as the water coming from domestic or industrial sources. Wastewater treatment includes physical, chemical, and biological treatment processes. Aerobic and anaerobic processes are utilized in biological treatment approach. However, the current biological approaches emit greenhouse gases (GHGs), methane, and carbon dioxide that contribute to global warming. Microalgae can be the alternative to treating wastewater as it is able to consume nutrients from wastewater loading and fix CO₂ as it undergoes photosynthesis. The utilization of microalgae in the system will directly reduce GHG emissions with low operating cost within a short period of time. The aim of this review is to discuss the uses of native microalgae species in palm oil mill effluent (POME) and flue gas remediation. In addition, the discussion on the optimal microalgae cultivation parameter selection is included as this is significant for effective microalgae-based treatment operations.     

Odor Threshold Measurement by Dynamic Olfactometry: Significant Operational Variables

Abstract

Combustion flue gases of three different industrial boilers firing miscellaneous fuels were monitored for a twoweek period. Nitric oxide (NO), sulfur dioxide (SO₂), carbon monoxide (CO), carbon dioxide (CO₂), and total hydrocarbons (CxHy) were continuously measured using single-component gas analyzers in parallel with a lowresolution Fourier Transform Infrared (FTIR) gas analyzer. Hydrogen chloride (HCl) was measured continuously using the FTIR analyzer and semi-continuously using a traditional liquid-absorption technique. Nitrous oxide (N₂O), nitrogen dioxide (NO₂), and water vapor (H₂O) were continuously measured using the FTIR analyzer only. Laboratory tests were conducted prior to the field measurements to assess the detection limits of the different measurement methods for each gas component. No significant differences were found between the results of the low-resolution FTIR analyzer and the single-component analyzers or the liquid absorption method.     

Mixotrophic cultivation of microalgae using industrial flue gases for biodiesel production

In the present study, an attempt has been made to grow microalgae Scenedesmus quadricauda, Chlorella vulgaris and Botryococcus braunii in mixotropic cultivation mode using two different substrates, i.e. sewage and glucose as organic carbon sources along with flue gas inputs as inorganic carbon source. The experiments were carried out in 500 ml flasks with sewage and glucose-enriched media along with flue gas inputs. The composition of the flue gas was 7 % CO₂, 210 ppm of NO _x and 120 ppm of SO _x . The results showed that S. quadricauda grown in glucose-enriched medium yielded higher biomass, lipid and fatty acid methyl esters (FAME) (biodiesel) yields of 2.6, 0.63 and 0.3 g/L, respectively. Whereas with sewage, the biomass, lipid and FAME yields of S. quadricauda were 1.9, 0.46, and 0.21 g/L, respectively. The other two species showed closer results as well. The glucose utilization was measured in terms of Chemical Oxygen Demand (COD) reduction, which was up to 93.75 % by S. quadricauda in the glucose-flue gas medium. In the sewage-flue gas medium, the COD removal was achieved up to 92 % by S. quadricauda. The other nutrients and pollutants from the sewage were removed up to 75 % on an average by the same. Concerning the flue gas treatment studies, S. quadricauda could remove CO₂ up to 85 % from the flue gas when grown in glucose medium and 81 % when grown in sewage. The SO _x and NO _x concentrations were reduced up to 50 and 62 %, respectively, by S. quadricauda in glucose-flue gas medium. Whereas, in the sewage-flue gas medium, the SO _x and NO _x concentrations were reduced up to 45 and 50 %, respectively, by the same. The other two species were equally efficient however with little less significant yields and removal percentages. This study laid emphasis on comparing the feasibility in utilization of readily available carbon sources like glucose and inexpensive leftover carbon sources like sewage by microalgae to generate energy coupled with economical remediation of waste. Therefore on an industrial scale, the sewage is more preferable. Because the results obtained in the laboratory demonstrated both sewage and glucose-enriched nutrient medium are equally efficient for algae cultivation with just a slight difference. Essentially, the sewage is cost effective and easily available in large quantities compared to glucose.     

Effect of Flue Dust on the Vanadium Oxide Catalyst Utilized by the Contact Oxidation Process

Concepts for controlling SO₂ from fossil fuels can be separated into two main categories: (1) Residual and vacuum gas oil desulfurization and (2) Flue gas desulfurization. The Kiyoura-T.I.T. process confines itself to the desulfurization of flue gas. It employs vandium oxide as a catalyst which oxidizes the sulfur dioxide to trioxide, followed by a gaseous phase reaction of ammonia. The end product, ammonium sulfate is removed by an electrostatic precipitator. (The details were presented at annual meetings of APCA in 1966 and 1967 as 1 and II.) Flue gas is passed through cyclone and dust filter to remove dust. Under normal operating conditions almost all of the dust is removed at the filters. The author carried out experiments to determine whether there was any effect on the activity of the catalyst, assuming that a portion of the dust escapes into the stream along the flue. It has been generally accepted that in fuel oil firing steam power plants, about 100 mg./nm³ of dust including carbon, hydrocarbon, and ash are normally contained in the flue stream. The carbon and hydrocarbon is oxidized readily at the filters and exists only as ash. An amount of ash equivalent to the amount assumed to have settled on the catalyst over a period of 3–12 months, was placed on the catalyst, and experiments were carried out. The SO₂ conversion efficiency was measured and found to be over 93%. The results showed that at the actual operational temperature of 450°C, ash had practically no effect at all.     

The study on biomass fraction estimate methodology of municipal solid waste incinerator in Korea

In Korea, the amount of greenhouse gases released due to waste materials was 14,800,000 t CO₂eq in 2012, which increased from 5,000,000 t CO₂eq in 2010. This included the amount released due to incineration, which has gradually increased since 2010. Incineration was found to be the biggest contributor to greenhouse gases, with 7,400,000 t CO₂eq released in 2012. Therefore, with regards to the trading of greenhouse gases emissions initiated in 2015 and the writing of the national inventory report, it is important to increase the reliability of the measurements related to the incineration of waste materials.

This research explored methods for estimating the biomass fraction at Korean MSW incinerator facilities and compared the biomass fractions obtained with the different biomass fraction estimation methods. The biomass fraction was estimated by the method using default values of fossil carbon fraction suggested by IPCC, the method using the solid waste composition, and the method using incinerator flue gas.

The highest biomass fractions in Korean municipal solid waste incinerator facilities were estimated by the IPCC Default method, followed by the MSW analysis method and the Flue gas analysis method. Therefore, the difference in the biomass fraction estimate was the greatest between the IPCC Default and the Flue gas analysis methods. The difference between the MSW analysis and the flue gas analysis methods was smaller than the difference with IPCC Default method. This suggested that the use of the IPCC default method cannot reflect the characteristics of Korean waste incinerator facilities and Korean MSW.

Implications: Incineration is one of most effective methods for disposal of municipal solid waste (MSW). This paper investigates the applicability of using biomass content to estimate the amount of CO₂ released, and compares the biomass contents determined by different methods in order to establish a method for estimating biomass in the MSW incinerator facilities of Korea. After analyzing the biomass contents of the collected solid waste samples and the flue gas samples, the results were compared with the Intergovernmental Panel on Climate Change (IPCC) method, and it seems that to calculate the biomass fraction it is better to use the flue gas analysis method than the IPCC method. It is valuable to design and operate a real new incineration power plant, especially for the estimation of greenhouse gas emissions.     

Nitrogen oxides emissions from the MILD combustion with the conditions of recirculation gas

The nitrogen oxides (NO_x) reduction technology by combustion modification which has economic benefits as a method of controlling NO_x emitted in the combustion process, has recently been receiving a lot of attention. Especially, the moderate or intense low oxygen dilution (MILD) combustion which applied high temperature flue gas recirculation has been confirmed for its effectiveness with regard to solid fuel as well. MILD combustion is affected by the flue gas recirculation ratio and the composition of recirculation gas, so its NO_x reduction efficiency is determined by them. In order to investigate the influence of factors which determine the reduction efficiency of NO_x in MILD coal combustion, this study changed the flow rate and concentration of nitrogen (N₂), carbon dioxide (CO₂) and steam (H₂O) which simulate the recirculation gas during the MILD coal combustion using our lab-scale drop tube furnace and performed the combustion experiment. As a result, its influence by the composition of recirculation gas was insignificant and it was shown that flue gas recirculation ratio influences the change of NO_x concentration greatly. Implications: We investigated the influence of factors determining the nitrogen oxides (NO_x) reduction efficiency in MILD coal combustion, which applied high-temperature flue gas recirculation. Using a lab-scale drop tube furnace and simulated recirculation gas, we conducted combustion testing changing the recirculation gas conditions. We found that the flue gas recirculation ratio influences the reduction of NO_x emissions the most.     

Early atmospheric detection of carbon dioxide from carbon capture and storage sites

The early atmospheric detection of carbon dioxide (CO₂) leaks from carbon capture and storage (CCS) sites is important both to inform remediation efforts and to build and maintain public support for CCS in mitigating greenhouse gas emissions. A gas analysis system was developed to assess the origin of plumes of air enriched in CO₂, as to whether CO₂ is from a CCS site or from the oxidation of carbon compounds. The system measured CO₂ and O₂ concentrations for different plume samples relative to background air and calculated the gas differential concentration ratio (GDCR = ?ΔO₂/ΔCO₂). The experimental results were in good agreement with theoretical calculations that placed GDCR values for a CO₂ leak at 0.21, compared with GDCR values of 1–1.8 for the combustion of carbon compounds. Although some combustion plume samples deviated in GDCR from theoretical, the very low GDCR values associated with plumes from CO₂ leaks provided confidence that this technology holds promise in providing a tool for the early detection of CO₂ leaks from CCS sites. Implications: This work contributes to the development of a cost-effective technology for the early detection of leaks from sites where CO₂ has been injected into the subsurface to enhance oil recovery or to permanently store the gas as a strategy for mitigating climate change. Such technology will be important in building public confidence regarding the safety and security of carbon capture and storage sites.     

From Air Repair to EM: A&WMA’s Publications through a Century of Change

Abstract

This paper analyzes the natural desulfurization process taking place in coal-fired units using Greek lignite. The dry scrubbing capability of Greek lignite appears to be extremely high under special conditions, which can make it possible for the units to operate within the legislative limits of sulfur dioxide (SO₂) emissions. According to this study on several lignite-fired power stations in northern Greece, it was found that sulfur oxide emissions depend on coal rank, sulfur content, and calorific value. On the other hand, SO₂ emission is inversely proportional to the parameter y _CO2max, which is equal to the maximum carbon dioxide (CO₂) content by vol ume of dry flue gas under stoichiometric combustion. The desulfurization efficiency is positively correlated to the molar ratio of decomposed calcium carbonate to sulfur and negatively correlated to the free calcium oxide content of fly ash.     

Simultaneous removal of sulfur dioxide and polycyclic aromatic hydrocarbons from incineration flue gas using activated carbon fibers

Incineration flue gas contains polycyclic aromatic hydrocarbons (PAHs) and sulfur dioxide (SO₂). The effects of SO₂ concentration (0, 350, 750, and 1000 ppm), reaction temperature (160, 200, and 280 °C), and the type of activated carbon fibers (ACFs) on the removal of SO₂ and PAHs by ACFs were examined in this study. A fluidized bed incinerator was used to simulate practical incineration flue gas. It was found that the presence of SO₂ in the incineration flue gas could drastically decrease removal of PAHs because of competitive adsorption. The effect of rise in the reaction temperature from 160 to 280 °C on removal of PAHs was greater than that on SO₂ removal at an SO₂ concentration of 750 ppm. Among the three ACFs studied, ACF-B, with the highest microporous volume, highest O content, and the tightest structure, was the best adsorbent for removing SO₂ and PAHs when these gases coexisted in the incineration flue gas.

ImplicationsSimultaneous adsorption of sulfur dioxide (SO₂) and polycyclic aromatic hydrocarbons (PAHs) emitted from incineration flue gas onto activated carbon fibers (ACFs) meant to devise a new technique showed that the presence of SO₂ in the incineration flue gas leads to a drastic decrease in removal of PAHs because of competitive adsorption. Reaction temperature had a greater influence on PAHs removal than on SO₂ removal. ACF-B, with the highest microporous volume, highest O content, and tightest structure among the three studied ACFs, was found to be the best adsorbent for removing SO₂ and PAHs.     

Investigation of Selective Catalytic Reduction Impact on Mercury Speciation under Simulated NOx Emission Control Conditions

Abstract

Selective catalytic reduction (SCR) technology increasingly is being applied for controlling emissions of nitrogen oxides (NO_x) from coal-fired boilers. Some recent field and pilot studies suggest that the operation of SCR could affect the chemical form of mercury (Hg) in coal combustion flue gases. The speciation of Hg is an important factor influencing the control and environmental fate of Hg emissions from coal combustion. The vanadium and titanium oxides, used commonly in the vanadia-titania SCR catalyst for catalytic NO_x reduction, promote the formation of oxidized mercury (Hg²⁺).

The work reported in this paper focuses on the impact of SCR on elemental mercury (Hg⁰) oxidation. Bench-scale experiments were conducted to investigate Hg⁰ oxidation in the presence of simulated coal combustion flue gases and under SCR reaction conditions. Flue gas mixtures with different concentrations of hydrogen chloride (HCl) and sulfur dioxide (SO₂) for simulating the combustion of bituminous coals and subbituminous coals were tested in these experiments. The effects of HCl and SO₂ in the flue gases on Hg⁰ oxidation under SCR reaction conditions were studied. It was observed that HCl is the most critical flue gas component that causes conversion of Hg⁰ to Hg²⁺ under SCR reaction conditions. The importance of HCl for Hg⁰ oxidation found in the present study provides the scientific basis for the apparent coal-type dependence observed for Hg⁰ oxidation occurring across the SCR reactors in the field.     

Recovering CO2 From Large− and Medium-Size Stationary Combustors

This paper summarizes the results of research conducted at Ar-gonne National Laboratory (ANL) to develop and design a novel method for the recovery of CO₂ from flue gases. The basic process concept Involves the combustion of a hydrocarbon fuel using a mixture of oxygen and carbon dioxide (or CO₂ and H₂0) rather than air as the oxidant, which results In a product stream that contains primarily CO₂ and H₂O. This stream Is then dried and conditioned to meet the specifications of the end user, A slip stream of CO₂ (or CO₂, and H₂0) is used as a diluent in the combustion chamberto maintain a flame temperature equivalent to the temperature that would otherwise be obtained using air as an oxidant. The cost-effectiveness of the process in recovering C0₂ is dependent on the scale of the operation, the type of fuel used, the cost of oxygen, and the cost of capital. The sensitivity of the cost of the recovered C0₂ to these variables Is discussed, and a model for estimating the cost of CO₂ recovered using the ANL process Is presented.     

Blue carbon in human-dominated estuarine and shallow coastal systems

Estuarine and shallow coastal systems (ESCS) are recognized as not only significant organic carbon reservoirs but also emitters of CO₂ to the atmosphere through air–sea CO₂ gas exchange, thus posing a dilemma on ESCS’s role in climate change mitigation measures. However, some studies have shown that coastal waters take up atmospheric CO₂ (C_atm), although the magnitude and determinants remain unclear. We argue that the phenomenon of net uptake of C_atm by ESCS is not unusual under a given set of terrestrial inputs and geophysical conditions. We assessed the key properties of systems that show the net C_atm uptake and found that they are often characteristic of human-dominated systems: (1) input of high terrestrial nutrients, (2) input of treated wastewater in which labile carbon is highly removed, and (3) presence of hypoxia. We propose that human-dominated ESCS are worthy of investigation as a contributor to climate change mitigation.     

NOx Reduction in a Gas Fired Utility Boiler by Combustion Modifications

Data on the effect of several combustion modifications on the formation of nitrogen oxides and on boiler efficiency were acquired and analyzed for a 110 MW gas fired utility boiler. The results from the study showed that decreasing the oxygen in the flue gas from 2.2% to 0.6% reduced the NO_x formation by 33% and also gave better boiler efficiencies. Flue gas recirculation through the bottom of the firebox was found to be ineffective. Staged combustion was found to reduce the NO_x emissions by as much as 55 % while decreasing the efficiency by about 5%. Adjustment of the burner air registers reduced the NO_x formation by about 20 ppm. The lowest NO_x emissions of 42 ppm (at about 3% O₂) in the stack was obtained for air only to one top burner and 0.5% oxygen in the flue gas.     

Stable carbon isotope ratio in atmospheric CO2 collected by new diffusive devices

In this paper, stable carbon isotope ratios (δ ¹³C) were determined in the atmosphere by using a Ca-based sorbent, CaO/Ca₁₂Al₁₄O₃₃ 75:25 w/w, for passively collecting atmospheric CO₂, in both field and laboratory experiments. Field measurements were conducted in three environments characterized by different carbon dioxide sources. In particular, the environments under consideration were a rather heavily trafficked road, where the source of CO₂ is mostly vehicle exhaust, a rural unpolluted area, and a private kitchen where the major source of CO₂ was gas combustion. Samplers were exposed to the free atmosphere for 3 days in order to allow collection of sufficient CO₂ for δ¹³C analysis, then the collected CO₂ was desorbed from the adsorbent with acid treatment, and directly analyzed by nondispersive infrared (NDIR) instrument. δ ¹³C results confirmed that the samplers collected representative CO₂ samples and no fractionation occurred during passive trapping, as also confirmed by an appositely designed experiment conducted in the laboratory. Passive sampling using CaO/Ca₁₂Al₁₄O₃₃ 75:25 w/w proved to be an easy and reliable method to collect atmospheric carbon dioxide for δ ¹³C analysis in both indoor and outdoor places.     

Application of gas diffusion biocathode in microbial electrosynthesis from carbon dioxide

Microbial catalysis of carbon dioxide (CO₂) reduction to multi-carbon compounds at the cathode is a highly attractive application of microbial electrosynthesis (MES). The microbes reduce CO₂ by either taking the electrons or reducing the equivalents produced at the cathode. While using gaseous CO₂ as the carbon source, the biological reduction process depends on the dissolution and mass transfer of CO₂ in the electrolyte. In order to deal with this issue, a gas diffusion electrode (GDE) was investigated by feeding CO₂ through the GDE into the MES reactor for its reduction at the biocathode. A combination of the catalyst layer (porous activated carbon and Teflon binder) and the hydrophobic gas diffusion layer (GDL) creates a three-phase interface at the electrode. So, CO₂ and reducing equivalents will be available to the biocatalyst on the cathode surface. An enriched inoculum consisting of acetogenic bacteria, prepared from an anaerobic sludge, was used as a biocatalyst. The cathode potential was maintained at ?1.1 V vs Ag/AgCl to facilitate direct and/or hydrogen-mediated CO₂ reduction. Bioelectrochemical CO₂ reduction mainly produced acetate but also extended the products to ethanol and butyrate. Average acetate production rates of 32 and 61 mg/L/day, respectively, with 20 and 80 % CO₂ gas mixture feed were achieved with 10 cm² of GDE. The maximum acetate production rate remained 238 mg/L/day for 20 % CO₂ gas mixture. In conclusion, a gas diffusion biocathode supported bioelectrochemical CO₂ reduction with enhanced mass transfer rate at continuous supply of gaseous CO₂.

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Simultaneous removal of NOx,SO2, and Hg from flue gas in FGD absorber with oxidant injection (NaClO2)– full-scale investigation

ABSTRACT

This article presents the results of an industrial-scale study (on 400 MW_e lignite fired unit) of simultaneous NO_x, SO₂, and Hg^T removal in FGD absorber with oxidant injection (NaClO₂) into flue gas. It was confirmed that the injection of sodium chlorite upstream the FGD (Flue Gas Desulfurization) absorber oxidize NO to NO₂, Hg⁰ to Hg²⁺, and enhancing NO_x and Hg^T removal efficiency from exhaust gas in FGD absorber. Mercury removal efficiency grows with the rise of degree of oxidation NO to NO₂ and was limited by the phenomenon of re-emission. For NO_x removal the most critical parameters is slurry pH and temperature. There was no negative effect on sulfur dioxide removal efficiency caused by oxidant injection in tested FGD absorber. Based on the data provided, NO_x and Hg^T emissions can be reduced by adjusting the FGD absorber operating parameters combined with oxidant injection.     

Electricity from Fossil Fuels without CO2 Emissions: Assessing the Costs of Carbon Dioxide Capture and Sequestration in U.S. Electricity Markets

ABSTRACT

The decoupling of fossil-fueled electricity production from atmospheric CO₂ emissions via CO₂ capture and sequestration (CCS) is increasingly regarded as an important means of mitigating climate change at a reasonable cost. Engineering analyses of CO₂ mitigation typically compare the cost of electricity for a base generation technology to that for a similar plant with CO₂ capture and then compute the carbon emissions mitigated per unit of cost. It can be hard to interpret mitigation cost estimates from this plant-level approach when a consistent base technology cannot be identified. In addition, neither engineering analyses nor general equilibrium models can capture the economics of plant dispatch. A realistic assessment of the costs of carbon sequestration as an emissions abatement strategy in the electric sector therefore requires a systems-level analysis. We discuss various frameworks for computing mitigation costs and introduce a simplified model of electric sector planning. Results from a “bottom-up” engineering-economic analysis for a representative U.S. North American Electric Reliability Council (NERC) region illustrate how the penetration of CCS technologies and the dispatch of generating units vary with the price of carbon emissions and thereby determine the relationship between mitigation cost and emissions reduction.     

Pilot project at Hazira,India, for capture of carbon dioxide and its biofixation using microalgae

The objective of the present study was to set up a small-scale pilot reactor at ONGC Hazira, Surat, for capturing CO₂ from vent gas. The studies were carried out for CO₂ capture by either using microalgae Chlorella sp. or a consortium of microalgae (Scenedesmus quadricauda, Chlorella vulgaris and Chlorococcum humicola). The biomass harvested was used for anaerobic digestion to produce biogas. The carbonation column was able to decrease the average 34 vol.% of CO₂ in vent gas to 15 vol.% of CO₂ in the outlet gas of the carbonation column. The yield of Chlorella sp. was found to be 18 g/m²/day. The methane yield was 386 l CH₄/kg VS_fed of Chlorella sp. whereas 228 l CH₄/kg VS_fed of the consortium of algae.     

Carbon emission from global hydroelectric reservoirs revisited

Substantial greenhouse gas (GHG) emissions from hydropower reservoirs have been of great concerns recently, yet the significant carbon emitters of drawdown area and reservoir downstream (including spillways and turbines as well as river reaches below dams) have not been included in global carbon budget. Here, we revisit GHG emission from hydropower reservoirs by considering reservoir surface area, drawdown zone and reservoir downstream. Our estimates demonstrate around 301.3 Tg carbon dioxide (CO₂)/year and 18.7 Tg methane (CH₄)/year from global hydroelectric reservoirs, which are much higher than recent observations. The sum of drawdown and downstream emission, which is generally overlooked, represents 42 % CO₂ and 67 % CH₄ of the total emissions from hydropower reservoirs. Accordingly, the global average emissions from hydropower are estimated to be 92 g CO₂/kWh and 5.7 g CH₄/kWh. Nonetheless, global hydroelectricity could currently reduce approximate 2,351 Tg CO₂eq/year with respect to fuel fossil plant alternative. The new findings show a substantial revision of carbon emission from the global hydropower reservoirs.     

Environmental building policy by the use of microalgae and decreasing of risks for Canadian oil sand sector development

Environmental building recommendations aimed towards new environmental policies and management-changing decisions which as example demonstrated in consideration of the problems of Canadian oil sands operators. For the implementation of the circular economic strategy, we use an in-depth analysis of reported environmental after-consequence on all stages of the production process. The study addressed the promotion of innovative solutions for greenhouse gas emission, waste mitigation, and risk of falling in oil prices for operators of oil sands with creating market opportunities. They include the addition of microalgae biomass in tailings ponds for improvement of the microbial balance for the water speedily cleaning, recycling, and reusing with mitigation of GHG emissions. The use of food scraps for the nutrition of microalgae will reduce greenhouse gas emission minimally, on 0.33 MtCO₂eq for Alberta and 2.63 MtCO₂eq/year for Canada. Microalgae-derived biofuel can reduce this emission for Alberta on 11.9–17.9 MtCO₂eq and for Canada on 71–106 MtCO₂eq/year, and the manufacturing of other products will adsorb up to 135.6 MtCO₂ and produce 99.2 MtO₂. The development of the Live Conserve Industry and principal step from non-efficient protection of the environment to its cultivation in a large scale with mitigation of GHG emission and waste as well as generating of O₂ and value-added products by the use of microalgae opens an important shift towards a new design and building of a biological system.